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Journal of Paleontology 92(4):713–733
(1995), Venczel (2008), Schoch and Rasser (2013), Naylor (1978b), and Marjanović and Witzmann (2015). We included a variety of characters, comprising skeletal, behavioral (including reproductive), soft-tissue, and geographic characters in this matrix, and we coded soft-tissue and behavioral characters as unknown for fossil taxa. We assembled the matrix of this study in Mesquite 2.75
(Maddison and Maddison, 2011), then ran a heuristic analysis using the Phylogenetic Analysis Using Parsimony program Version 4.0a152 (PAUP; Swofford, 2002) to produce simple parsimony trees. We elected to use simple parsimony for our analyses because they contained multistate, ordered, and unordered characters. We analyzed a total of 108 characters and a total of 40 taxa in a matrix using all characters, including both unconstrained and molecularly constrained (via consensus data assembled in Marjanović and Witzmann, 2015) from Zhang et al. (2008) and Pyron (2014) analyses. With 108 characters (33 ordered), this analysis is the largest morpholo- gical matrix used for analyzing salamandrid evolutionary relationships to date. In another round of heuristic analyses, we removed fossil newt taxa known only from vertebrae (Koalliella, Taricha miocenica, Notophthalmus crassus [in this case, including the fossils sometimes assigned to Notophthalmus slaughteri; Holman, 2006], and Notophthalmus robustus) prior to running unconstrained and molecularly constrained analyses. We coded characters inapplicable or unknown for a taxon (e.g., soft tissue characters when coding fossil taxa) with question marks. Bracketed numbers indicate a character’s original number from its referenced source (Supplementary Data Sets 1, 2). We performed a heuristic search with 1000 repetitions of stepwise addition with random addition sequence using the sectorial search algorithm setting, and TBR (tree bisection and reconnection), with all characters weighted equally. We calculated the Consistency Index, Retention Index, and Homoplasy index, as well as strict consensus trees, in PAUP. Ambystoma and Dicamptodon are outgroups for our
analyses. Within Taricha, T. sierrae was combined with T. torosa because there was not enough morphological character data available, and few positively identified skeletal specimens available to distinguish the species from T. torosa. As such, T. sierra as presently understood scores identically to T. torosa in our morphological phylogenies. Because of our lack of data, we did not include Notophthalmus slaughteri because it may be synonymous with Notophthalmus crassus, and we have no direct observations of either potential species (Holman, 2006).
We modified the assigned character states for taxa in a few
cases for previously used characters based on personal observations and/or previously published literature; this is particularly true for Tylototriton in character 71, and character 61 for extant species of Taricha. Character 71 refers to the presence of ribs either as short rods (0) or as long as three vertebral centra (1), yet in at least Tylototriton verrucosus, the ribs do not quite exhibit character state 1 (based on Nussbaum and Brodie, 1982) because they are closer to the length of two vertebral centra, while Tylototriton asperrimus was initially assigned to Echinotriton partially because their trunk ribs fit character state 1 (Nussbaum et al., 1995). We assigned both
states 0 and 1 to Tylototriton as a genus. The length of the ribs in Taricha oligocenica, and to a lesser extent, Taricha lindoei, are visually similar to those of Tylototrion verrucosus, both in terms of length and in the number, structure, and orien- tation of the epipleural processes, which we discuss briefly later. We therefore assigned a character state of 0 to these taxa, but recommend further investigation of this character as a whole, because the ribs of Tylototriton verrucosus and Taricha oligocenica do not quite fit either character state (longer than simple, short rods, but shorter than described in state 1).
Repositories and institutional abbreviations.—JODA, John Day Fossil Beds National Monument; UALVP, University of Alberta Laboratory for Vertebrate Paleontology; UCMP, Uni- versity of California – Berkeley Museum of Paleontology; UCMP, University of California – Berkeley Museum of Vertebrate Zoology; UOMNH, University of Oregon Museum of Natural History.
Systematic paleontology Class Amphibia Gray, 1825
Subclass Lissamphibia Haeckel, 1866 Order Caudata Scopoli, 1777
Suborder Salamandroidea Fitzinger, 1826 Family Salamandridae Goldfuss, 1820 Genus Taricha Gray, 1850
Type species.—Taricha torosa (Rathke, 1833).
Diagnosis.—Osteologic characters of extant Taricha include a low to moderately high neural spine without an extensive pitted dermal cap (Wake and Özeti, 1969; Naylor, 1978b). The genus Taricha also possesses concave inter-prezygapophyseal neural arch margins (Boardman and Schubert, 2011). The premaxillae are fused, nasals are separated, the rib processes do not extend past the body wall (no costal grooves), anterior caudal ribs (caudosacral ribs of Estes, 1981) are absent, and the cotyles of the vertebrae appear horizontally oval (Estes, 1981). The hyo- branchium possesses a cartilaginous, mineralized first basi- branchial and second ceratobranchial, but lacks the second basibranchial and anterior radii. Taricha also has a reduced interradial cartilage (Estes, 1981).
Remarks.—Taricha’s closest relative is Notophthalmus, the only other North American newt genus. It is important to note that extinct species Taricha oligocenica (Van Frank, 1955) and Taricha miocenica (Tihen, 1974) possess pitted spine tables on the dorsal side of their vertebrae, leading to questions about the ancestral state of North American newts. Weaver (1963) deter- mined that the shape of the vomerine (then incorrectly thought to be “prevomerine”; Atkins and Franz-Odendaal, 2015; Marjanović and Witzmann, 2015) tooth row of extant Taricha is distinguishably different between Taricha granulosa, which displays the plesiomorphic V-shaped arrangement, and Taricha torosa, Taricha sierra, and Taricha rivularis, which all display a Y-shaped pattern.
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